Valve



Aug 17, 1955 A. A. BEUTLER 3,200,841

VALVE Filed June 2o, 196s Tlv I8 al 24 ATTORNEYS 3,200,841 VALVE ArthurA. Beutler, Kalamazoo, Mich., assigner to The New York Air BrakeCompany, a corporation of New Jersey Filed .lune 20, 1963, Ser. No.289,295 2 Claims. (Cl. 137-596) This invention relates to valve-s forcontrolling the flow of fluid to and from hydraulic motors.

A typical actuation circuit for a double-acting piston motor includes apump, a sump and a three-position directional control valve having inletand exhaust ports connected with the pump and sump, respectively, and apair of motor ports connected with opposite sides of the motor. Thedirectional control valve has a neutral position in which each motorport is isolated from the other three ports and the rnotor ishydraulically locked, a second position in which it establishes a supplypath from the inlet port to the first motor port and an exhaust pathfrom the second motor port to the exhaust port, and a third position inwhich it establishes a supply path from the inlet port to the secondmotor port and an exhaust path from the irst motor port to the exhaustport. In some installations, for example, the blade raising and loweringcircuit of a bulldozer, the load being actuated tends t contract oneyside of the motor, and in other installations, for instance, the masttilting circuit of a fork lift truck, the load may tend to contracteither side of the motor. In installations such as these, if thedirectional control valve is in a position to establish a supply path tothe motor port connected with the coutracting side of the motor whensupply pressure falls be-low load pressure, as a result, for example, offailure of the pump or a break in the supply line connecting the pumpwith the directional control valve, the motor will drop the load.Because of this, it is necessary to include in one or both supply pathsa check valve which serves to sustain the load by preventing reverseflow through the supply path.

Another problem encountered in circuits of this kind is that ofpreventing the development of excessive pressures in the contractingside of the motor when the directional control valve is in neutralposition. Although these actuation circuits include a system reliefvalve, this valve is located upstream of the actual valving mechanism inthe directional control valve and thus is isolated from the motor portswhen that valve is in neutral position. Therefore, the system reliefvalve is not effective to relieve excessive pressures in one or bothsides of the motor resulting from external loads applied to the motorwhen the directional control valve is in neutral position, or from themomentum of the actuated load itself in those cases where the operatorsuddenly returns the directional control valve to neutral position whenthe load is in motion. Because of this, one or both sides of the motorfrequently are provided with overload relief valves.

From the standpoint of versatility and simplicity, it is desirable tolocate both the load drop check valve and the overload relief valve forone or both sides of the motor in the movable member of the directionalcontrol valve. One such arrangement is disclosed in Ruhl Patent2,946,347, issued July 26, 1960. However, in the combined check andrelief valve shown in this patent, both sides of the pilot poppet aresubjected to substantially the same pressure once the main relief valveopens and it has been found that this changes the relief characteristicsand makes the unit erratic.

The object of this invention is to provide an improved form of check andrelief valve which is mounted in the movable member of the directionalcontrol valve and i. United States Patent O 3,299,841 Patented Aug. 17,1965 which eliminates the disadvantage of the device shown in the Ruhlpatent mentioned above. In addition, the combined check and relief valveof this invention is less cost-ly, simpler and more reliable than itspredecessor.

The preferred form of the invention is described herein with referenceto the accompanying drawing whose single figure is a cross-sectionalview of a threeposition, sliding plunger, directional control valve ofthe open center type incorporating the invention.

As shown in the drawing, the directional control valve comprises ahousing 11 containing inlet and exhaust ports 12 and 13, respectively,and a through valve bore 14. The bore 14 is encircled by sevenlongitudinally spaced chambers 15 through 19, 21 and 22. Annularchambers 15, 18 and 22 communicate with exhaust port 13 through exhaustmanifold 23, and annular chambers 17 and 19 communicate with inlet port12 through inlet manifold 24. Annular chambers 16 and 21 are connectedwith a pair of motor ports (not shown). A conventional, pilot-operatedsystem relief valve 25 limits the pressure in inlet manifold 24 bybypassing fluid to the exhaust manifold 23.

Slidable in bore 14 is a valve plunger 26 formed with two spaced grooves27 and 28 that define three lands 29, 31 and 32. Extending inward fromopposite ends of plunger 26 are a pair of axial bores 33 and 34 whoseouter ends are closed and sealed by threaded plugs 35 and 36,respectively. Axial bore 33 is intersected by two spaced sets of radialpassages 37 and 38, and axial bore 34 is` intersected by two similarsets of passages 39 and 41. However, it will be observed that unlike itscounterpart 37 at the left side of plunger 26, passages 41 register withthe associated motor chamber 21 when the plunger 62 is in theillustrated neutral position. Each axial bore is provided with a step 42that. serves as a seat for the load drop check valve. Since it isassumed in this embodiment that the load drop check valve is requiredonly in that side of the plunger 26 controlling ilow to and from motorchamber 21, the seat in bore 33 actually is not required.

Reciprocable in axial bore 34 is a load drop check valve 43 having abeveled end 44 that serves as the head of the check valve and isarranged to seat on step 42. Bore 34 also contains a reciprocable sleeve45 formed with an end wall 46 that faces the left end of check valve 43.The space within bore 34 between the adjacent ends of sleeve 45 andcheck valve 43 is connected with radial passages 41 through axial andradial passages 47 and 4S, respectively, formed in the check valve. Endwall 45 contains an axial port 49, the right edge of which serves as aseat for the relief poppet 51 located within sleeve 45. The interior ofsleeve 45, which is the downstream side of the relief poppet, is incontinuous communication with exhaust port 13 through registering radialpassages 52 and 53 formed in sleeve 45 and plunger 26, respectively,chamber 22 and exhaust manifold 23. A coil compression spring 54,reacting between plug 36 and poppet 51, urges the relief valve closedand, through sleeve 45, also urges check valve 43 in the closingdirection. Thus, this single spring furnishes closing bias for bothvalves.

Operation In a typical installation, inlet port 12 is connected with apump 55, exhaust port 13 is connected wtin a sump 56, and the motorports communicating with annular chambers 16 and 21 are connected byconduits 57 and 58, respectively, with the opposite sides of adouble-acting piston motor 59. For purposes of this description, it isassumed that the device actuated by motor 59 exerts a load that tends tocontract the rod end of the motor and thus to pressurize annular chamber21.

When valve plunger 26 is in the illustrated neutral position, the ffuiddelivered to inlet port l2 from pump 55 flows directly to sump 56through inlet manifold 24, annular chambers 17 and 19, plunger grooves27 and 28, annular chamber 1S, exhaust manifold 23 and exhaust port 13.`Lands 29 and 31 isolate motor chambers 16 and 2i, respectively, fromcommunication with each other and with the other chambers. At this time,the load pressure in chamber 2l is transmitted to axial port 49 insleeve 45 via radial passages 41 and 48 and axial passage 47 where itacts upon the nose of poppet 51. Normally, this load pressure isinadequate to unseat the poppet against the opposing bias of spring 54.However, when excessive pressures are developed in the rod end of motor59, poppet 5l moves to the right and opens a relief path to sumpincluding the interior of sleeve 4S, radial passages 52 and 53, chamber22, exhaust manifold 23 and exhaust port 13. When the overload conditionhas subsided, poppet 51 moves to the left under the action of spring 54and closes this relief path.

Rightward movement of motor 59 is effected by shifting valve plunger 26to the right to its second position in 4which radial passages 37, 3S, 39and 4l register, respectively, with annular chambers 16, 17, 21 and 22,and lands 29 and '3i interrupt the open center unloading path betweenpump 55 and sump 56. The fluid delivered by pump 55 may now fiow to thehead end of motor 59 along a supply path comprising inlet port 12, inletmanifold 24, annular chamber i7, radial passages 38, axial bore 33,radial passages 37, annular chamber 16, and conduit 57. The fiuiddisplaced from the rod end of motor 59 is transmitted to axial bore 34through conduit 5S, annular chamber 21 and radial passages 39 where itacts upon the left end of check valve 43. Since the space Within sleeve45 is in continuous communication with annular chamber 22, check` valve43 and sleeve 45 are shifted to the right against the bias of spring 54by the fluid in the left end of bore 34, thereby opening a return pathto sump 56 including radial passages 41, annular chamber 22, exhaustmanifold 23 and exhaust port 13. Inasmuch as the cross-sectional area ofthe left end of check valve 43 is much greater than the cross-sectionalarea of port 49, a very small pressure differential is required to openthe check valve even though this valve and relief poppet 51 are biasedclosed by the same spring.

The operator stops rightward movement of motor 59 by returning valveplunger 26 to its neutral position. If the load acting on motor 59 islarge and is moving rapidly, its momentum may develop excessivekpressures in the rod end of motor 55* if the return path from this sideof the motor is interrupted suddenly. Should this happen, relief poppetSi will open in the manner described above and the overpressure will bedissipated.

Leftward movement of motor 59 is effected by shifting plunger 26 to theleft to a third position in which radial passages 37, 3d, 39 and 41register, respectively, with annular chambers 15, 16, 19 and 21, andlands 31 and 32 close the open center unloading path. Now, fluiddelivered by the pump 55 is transmitted to axial bore 34 through inletport l2, inlet manifold 24, annular chamber 19 and radial passages 39.When supply pressure rises to a value sufficient to overcome thecombined bias of spring S4 and the pressure force developed by the loadpressure acting on the right end of check valve 43, the check valveopens and allows the fluid in bore 34 to fioW to the rod end of motor 59through radial passages 4l, annular chamber 2i and conduit 58.Simultaneously, valve plunger 26 opens an exhaust path from the head endof motor 59 to sump 56 comprising conduit 57, annular chamber lr6,radial passages 38, axial bore 33, radial passages 37, annular chamber15, exhaust manifold 23 and exhaust port lf3. As in the previous case,movement of motor S@ is stopped by returning valve plunger 26 to itsneutral position.

lt will be observed that when valve plunger 26 is in the third position,the load pressure in radial passages 4l acts on an annular area at theleft end of check valve 43 having a radial width equal to the differencebetween the diameter of seat 42 and the outside diameter of the checkvalve, and develops a force that tends to open the check valve. However,since the entire right end of the check 'valve is subjected to the samepressure and develops a much larger force tending to close the valve7 itis apparent that should supply pressure fail While plunger 26 is in thethird position, valve 43 will close and preclude dropping of the load.It will be apparent that since spring 54 also biases check valve 43 inthe closing direction, it is not essential that load pressure develop onvalve 43 a net force tending to close it, and that a balance of pressureforces is all that actually is required in the illustrated embodiment.

As stated previously, the drawing and description relate only to thepreferred embodiment of the invention. Since changes can be made in the`structure of this embodiment without departing from the inventiveconcept, the following claims should provide the sole measure of thescope of the invention.

What I claim is:

1. A valve comprising (a) a housing containing a bore intersected bythree spaced chambers, there being a supply chamber, an exhaust chamberand an intermediate motor chamber;

(b) a valve member movable in the bore and containing an internalpassage intersected by first and second spaced through ports;

(c) the valve member having a first position in which the second throughport registers with the motor chamber, a second position in which therst, and second through ports register, respectively, with the supplyand motor chambers, and a third position in which the first and secondthrough ports register respectively with the motor and exhaust chambers;

(d) a check valve seat encircling the internal passage and locatedbetween the first and second through ports;

(e) a check valve head reciprocable in the internal passage between openand closed positions with respect to said seat for controlling flow fromthe first to the second through port;

(f) reaction surfaces on the check valve head subject to the pressure inthe second through port for developing forces that urge the head in boththe opening and the closing directions, the areas of the reactionsurfaces being so proportioned that the force urging the head in theopening direction does not exceed the force urging the head in theclosing direction;

(g) means defining a vent chamber within the valve member whichcommunicates with the exhaust chamber at least when the valve member isin the first position;

(h) a relief passage connecting the vent chamber with the second throughport, said relief passage constituting the sole fluid connection betweenthe vent charnber and the second through port; and

(i) a relief valve normally preventing ffowrfrorn the second port to thevent chamber through the relief passage but being responsive to thedifferential between the pressures in the second port and the ventchamber for opening the relief passage when the differential reaches apredetermined value.

2. A valve'cornprising (a) a housing containing a bore intersected bythree longitudinally spaced chambers, there being a supply chamber, anexhaust chamber and an intermediate motor chamber;

(b) a valve plunger reciprocable in the bore and containing alongitudinal bore intersected by first and second longitudinally spacedthrough ports;

(c) the plunger having a first position in which the second throughlport registers with the motor charn-4 ber, a second position in whichthe rst and second through ports register, respectively, with the supplyand motor chambers, and a third position in which the first and secondthrough ports register, respectively, With the motor and exhaustchambers;

(d) -a check valve seat encircling the longitudinal bore and locatedbetween the first and second through ports;

(e) a check valve reciprocable in the longitudinal bore and carrying ahead at one end arranged to engage said seat;

(f) a sleeve reciprocable in the longitudinal bore and having a closedend wall facing the end of the cheek Valve opposite the head;

(g) passage means connecting the second through port with the space inthe longitudinal bore between the check Valve and the sleeve;

(h) a relief port formed through said end wall;

(i) a relief poppet within said sleeve and seated in said relief port;

(j) a spring reacting between the plunger and the p0ppet and urging thepoppet toward its seat and the check Valve toward its seat; and

(k) means defining a relief passage connecting the interior of thesleeve with the exhaust chamber.

References Cited by the Examiner UNITED STATES PATENTS 2,946,347 7/60Ruhl 137-6l2.l

M. CARY NELSON, Primary Examiner.

15 HENRY T. KLINKSIEK,Exam1-ner.

1. A VALVE COMPRISING (A) A HOUSING CONTAINING A BORE INTERSECTED BYTHREE SPACED CHAMBERS, THERE BEING A SUPPLY CHAMBER, AN EXHAUST CHAMBERAND AN INTERMEDIATE MOTOR CHAMBER; (B) A VALVE MEMBER MOVALBE IN THEBORE AND CONTAINING AN INTERNAL PASSAGE INTERSECTED BY FIRST AND SECONDSPACED THROUGH PORTS; (C) THE VALVE MEMBER HAVING A FIRST POSITION INWHICH THE SECOND THROUGH PORT REGISTERS WITH THE MOTOR CHAMBER, A SECONDPOSITION IN WHICH THE FIRST, AND SECOND THROUGH PORTS REGISTER,RESPECTIVELY, WITH THE SUPPLY AND MOTOR CHAMBERS, AND A THIRD POSITIONIN WHICH THE FIRSAT AND SECOND THROUGH PORTS REGISTER RESPECTIVELY WITHTHE MOTOR AND EXHAUST CHAMBERS; (D) A CHECK VALVE SEAT ENCIRCLING THEINTERNAL PASSAGE AND LOCATED BETWEEN THE FIRST AND SECOND THROUGH PORTS;(E) A CHECK VALVE HEAD RECIPROCABLE IN THE INTERNAL PASSAGE BETWEEN OPENAND CLOSED POSITIONS WISTH RESPECT TO SAID SEAT FOR CONTROLLING FLOWFROM THE FIRST TO THE SECOND THROUGH PORT; (F) REACTION SURFACES ON THECHECK VALVE HEAD SUBJECT TO THE PRESSURE IN THE SECOND THROUGH PORT FORDEVELOPING FORCES THAT URGE THE HEAD IN BOTH THE OPENING AND THE CLOSINGDIRECTIONS, THE AREAS OF THE REACTION SURFACES BEING SO PROPORTIONEDTHAT THE FORCE URGING THE HEAD IN THE OPENING DIRECTION DOES NOT EXCEEDTHE FORCE URGING THE HEAD IN THE CLOSING DIRECTION; (G) MENS DEFINING AVENT CHAMBER WITHIN THE VALVE MEMBER WHICH COMMUNICATES WITH THE EXHAUSTCHAMBER AT LEAST WHEN THE VALVE MEMBER IS IN THE FIRST POSITION; (H) ARELIEF PASSAGE CONNECTING THE VENT CHAMBER WITH THE SECOND THROUGH PORT,SAID RELIEF PASSAGE CONSTITUTING THE SOLE FLUID CONNECTION BETWEEN THEVENT CHAMBER AND THE SECOND THROUGH PORT; AND (I) A RELIEF VALVENORMALLY PREVENTING FLOW FROM THE SECOND PORT TO THE VENT CHAMBERTHROUGH THE RELIEF PASSAGE BUT BEING RESPONSIVE TO THE DIFFERENTIALBETWEEN THE PRESSURES IN THE SECOND PORT AND THE VENT CHAMBER FOROPENING THE RELIEF PASSAGE WHEN THE DIFFERENTIAL REACHES A PREDETERMINEDVALUE.